As shown in FIG. 17 of this specification, a base plate connector has a plurality of long and thin terminal pins 3 which protrude from the rear face of a connector housing 2 and bend downwards. The anterior ends of the terminal pins 3 are aligned so as to fit with connecting holes H formed in a circuit base plate P. It is arranged so that, when attachment is carried out, the connector housing 2 is fixed at a specified position on the circuit base plate P, the anterior end of the terminal pins 3 being inserted 15 into the connecting holes H and being fixed by means of soldering M. The terminal pins are easily bent out of position, and so the connector housing 2 has an alignment plate 4 fixed thereon, this alignment plate 4 serving as a means for carrying out with certainty the insertion operation of the terminal pins 3 into the connecting holes H. The alignment plate 4 has position fixing holes 5 that correspond to the connecting holes H of the circuit base plate P. The anterior ends of the terminal pins 3 pass through the position fixing holes 5 and as a consequence the mutual positioning among the terminal pins 3 comes to correspond to the alignment of the connecting holes H.
In the state where the base plate connector 1 is attached to the circuit base plate P, if the connector housing 2, the alignment plate 4, and the circuit base plate P are subjected to a temperature change, due to the differing rates of thermal expansion of the different materials used, there is a possibility of a force applying so as to cause a relative shift in position between the position fixing holes 5 and the connecting holes H along a direction that is transverse to the terminal pins 3. However, in the case of the conventional alignment plate 4, since it is necessary to fix the position of the terminal pins 3 with a high degree of accuracy, the position fixing holes 5 are arranged to be of the minimum necessary size in order to prevent sideways movement of the terminal pins 3, as shown in FIG. 18. For this reason, if a transverse force applies so that the position fixing holes 5 shift in position with respect to the connecting holes H, this force is transmitted to the soldered portions M via the terminal pins 3, and stress on the soldered portions M increases. This may weaken or break the electrical connection.
The present invention has been developed after taking the above problem into account, and aims to prevent an increase in stress on the soldered portions joining the terminal pins to the circuit base plate as the ambient temperature changes.
According to the invention, there is provided a connector for attachment to a printed circuit board which comprises a connector housing having a plurality of elongate electrical terminals projecting therefrom in a first direction and an alignment member attached to said housing. The housing is adapted to retain the free ends of said terminals in a substantially fixed orientation with respect to the housing. The alignment member is movable with respect to the housing in the first direction from a temporary position to a final position. The terminals are tightly retained by said alignment member in the temporary position and loosely retained by said alignment member in the final position.
Such an alignment member has the advantage that the terminals are tightly retained for positioning with respect to the circuit board or other electrical component, yet are free to move relative to the alignment member once in the final position.
Preferably the alignment member is substantially planar and has a plurality of apertures to receive the tips of the terminals in sliding relationship. The apertures are preferably enlarged on the side of the circuit board or component to accommodate solder; this ensures that the eventual soldered connection of the terminals is strong and electrically sound.
In a preferred embodiment the terminals are waisted immediately behind the tip so as to be a loose fit in the alignment member when it has been moved to the final position. Alternatively, the terminal can be flanged outwardly behind the tip, and the flanged portion arranged to be a tight sliding fit in a respective aperture. In the final position the flange is moved out of the aperture to leave the terminal in said aperture with clearance.
The alignment member is preferably retained on the housing by detent means whereby it can be snapped from the temporary to the final positions. In the case where the components are of plastic or resin material the alignment member may have opposite projections for engagement in opposite parallel recesses of the housing. These recesses may comprise opposite parallel grooves to retain opposite edges of the alignment member, two grooves being provided on each side to define the temporary and final positions.
Preferably the alignment member is arranged between the housing and the circuit board or other electrical component. This arrangement ensures that simple pressure on the housing can automatically snap the alignment member to the final position where it remains sandwiched in place. This has the further advantage that the alignment member cannot move relative to the housing and thus place stress on the soldered connection of the terminals.